Loewe T, Baltruschat H
Institut für Physikalische und Theoretische Chemie, Universität Bonn, Römerstr. 164 D-53117, Bonn.
Phys Chem Chem Phys. 2005 Jan 21;7(2):379-84. doi: 10.1039/b412505n.
A new dynamic method for the measurement of pressure dependent kinetic and thermodynamic quantities is described and its successful operation demonstrated for two example systems. The pressure was modulated with an amplitude of only +/-1 bar or less by means of a piezo-transducer. The small effect on the reaction rate, potential or charge of the electrode can be detected using the lock in technique. The determination of the reaction volume of the redox couple Fe(CN)6(4-)/Fe(CN)6(3-) served as a control of the validity of the measurement and the reliability of the experimental approach. As a first model system the adsorption of hydrogen on polycrystalline Pt was studied. A volume of adsorption of 4.8 cm3 mol(-1) was found. The partial molar volume for protons in water (upsilon+ = -5.4 cm3 mol(-)) measured by Zana and Yeager, J. Phys. Chem., 1967, 71, 521-536, was used to establish that the partial molar volume of the adsorbed hydrogen was close to zero.
描述了一种用于测量压力相关动力学和热力学量的新动态方法，并在两个示例系统中展示了其成功运行。通过压电换能器将压力调制为仅±1巴或更小的幅度。使用锁相技术可以检测到对电极反应速率、电位或电荷的微小影响。氧化还原对Fe(CN)6(4-)/Fe(CN)6(3-)反应体积的测定用于控制测量的有效性和实验方法的可靠性。作为第一个模型系统，研究了氢气在多晶铂上的吸附。发现吸附体积为4.8 cm3 mol(-1)。Zana和Yeager在《物理化学杂志》1967年第71卷第521 - 536页测量的水中质子的偏摩尔体积(υ+ = -5.4 cm3 mol(-))被用于确定吸附氢的偏摩尔体积接近零。
